1. Field of the Invention
The present invention relates to contact assemblies for high voltage fuses, and more particularly, to contact elements and methods of assembly thereof in high voltage expulsion type fuses.
2. Description of the Prior Art
High voltage explusion fuses are well known in the art as exemplified by such patents as U.S. Pat. Nos. 3,267,235 -- Barta, 3,176,100 -- Barta, 3,575,683 -- Fahnoe, and 3,855,563 -- Cameron et al. The prior art expulsion fuses disclosed in the foregoing patents all utilize an arcing rod biased by a spring for a movement but which is retained against movement by a fusible element and a strain wire which are connected between one end of the arcing rod and some type of contact assembly. For example, in U.S. Pat. No. 3,176,100 -- Barta, the contact assembly comprises a stud mounted to the wall of a metal exhaust ferrule. In U.S. Pat. No. 3,575,683 -- Barta, the contact assembly comprises a terminal stud mounted to a bridging member which forms an integral part of an exhaust ferrule. In U.S. Pat No. 3,267,235 -- Barta the contact assembly comprises a bridge attached to the interior wall of the ferrule by soldering, brazing or some other similar technique, and a terminal rod which is bolted to the bridge. Finally, U.S. Pat. No. 3,855,563 -- Cameron et al. does not utilize a contact assembly as such, but merely folds the strain wire and fusible element over the edge of the insulator tube and crimps these elements with a metal ferrule. This latter technique is not particularly desirable since the fusible element and strain wire can easily become weakened or broken during the crimping operation or subsequent handling.
The present invention, as will be more fully described and disclosed herein, provides a contact assembly which is easily assembled, permits reliable positioning, remains in position during fuse operation, and resists burning out during fuse operation. Thus, the present invention is a desirable advance in the existing art.